Apparatus for the production of electrolytic iron



Jan. 19 1926.

- E. DUHME APPARATUS FOR THE PRODUCT ION 0F ELECTROLYTIC IRON Fil ed June 17, 1924 11 74 0018087751. E GA 8 FAIR \QOMBUBT/BLE ans HEA'HNG .sP/Icc cathode.

Patented Jan. 1926.

UNITED STATES PATENT OFFICE.

EMIL DUHME, O1? IBEBI LIN-CHABLOTTEI N BURG, GEBKANY, ASSIGNOR TO SIEMENS & HALSKE, AKTIENGESELLSCEAFT, OF SIEMENSS'IADT, NEAR BERLIN, cm,

A. CORPORATION OF GERMANY.

nrm'rus non 'rr'm raonuc'rron, or nmc'rnomr'rrc more.

Application filed June 17, 1924. Serial No. 726,609.

5 vented certain new and useful Im rovements in Apparatus for the Production of Electrolytic Iron, of which the following is a specification.-

Thls invention relates to improvements in apparatus for the production .of electrolytic iron and more particularly to an apparatus in which an anode of iron is immersed in the electrolytic, bath so that at the cathode electrolytic iron is deposited as product of the process.

It is an advantage that in such apparatus also inferior qualities of iron for instance cast iron, may be employed as material for the anodes. The impurities of m the cast iron have however'a very bad'efi'ect upon the process, inasmuch as particularly carbon or graphite particles, which are dissolved out of the anode reach the'cathode, settle down and form bulbs upon it, which is described as budding. First small unevennesses are formed-upon the cathode surface, which gradually grow into large branches and necessitate the interru tionof the processand the exchange 0 the It has already been proposed to interpose a filter between the anode and the cathode in order to prevent the impurities (carbon, graphite and the like) which get intothe electrolyte from the'anode from travelling to the cathode. Such filters are, however, expensive and increase the resistance of the electrolytic bath, with consequent losses of energy. The life of such filters is, furthermore, short since the pores of the filter become gradually enlarged during service.

The object of my invention is to keep the impurities of the electrolyte away from the cathode in another and improved manner and to avoid the interruption of the electrolysis and the exchange of the cathode before the process is finished. For this purpose it is necessary when using cast iron as anode material to choose a cast iron the carbon content of which is so high that I when the anode iron is dissolved a coherent skeleton of graphite and silicon, which is contained in every cast iron, remams beat the anode. According to the composition of the cast iron the content of carbon necessary for the formation of the coherent-skeleton varies and it is necessary in each "individual case to ascertain the proper content by tests. I have ascertained by extensive experiments that this skeleton is in most cases already obtained at a carbon content even as low as 3%. At the same. time the phosphorus contained in the anode iron is carried oil by thehydrogen generated at the anode under the influence of free hydrochloric acid in the form of phosphureted hydrogen.

The skeleton of graphite and silicon remaining behind at the anode shows generally only low mechanical strength, but its pores are close enough together to obstructthe free exit of the gases generated beneath 'its surface. Thus the danger arises that the gas bubbles generated below the surface of the skeleton gradually collect and finally cause the skeleton to drop off the mode. The V eleton then falls to the bottom ofthe apparatus in the form of a plate of 1 to 2 mm. thickness. I have now ascertained that it is possible to cause the skeleton firmly adhere to the anode, by keeping the current density at the anode lower than at the cathode which can be attained by making the surface of the anode of larger area than the surface of the cathode. I have, furthermore, ascertained that a particularly favorable efiect is produced, if the ratio of-the current density between the anodeand the cathode is 1: 6 or even eater.

The dropping off 0 the skeleton may also be prevented by employing a lower voltage in the bath and an electrolyte of weak acidity (content of acid). I have observed that at a cathode current density of 5 to 10 amperes per square decimetre the cathodes were still serviceable after days of continuous service. In order to be able to bring about the surface ratio 6: 1 of anode drawing.

iron on the cathode during the progress of the electrolysis is effectively prevented.

In order to prevent the impurities which have entered the electrolyte at the beginning of the process from reaching the oathode, it is advisable not to heat the electrolyte vessel from below, but to provide heating elements within the electrolyte so that the temperature of the liquid is lowest at the bottom of the vessel. It has been ascertained that it is particularly advantageous to dispose the heating elements in appropriate proximity to the cathodes, in other words as far as possible away from the anodes, so that a circulation of the liquid takes place in such a manner that the liquid ascends along the cathode and descends along the anode. The distance of the heating element from the anodes may still further be lengthened by placing the heating device not only close to the cathode, but actually into it. By the circulation of the liquid produced in this manner, as already explained, it ascends along the cathode and descends along the anodes, the impurities dissolved out of the anodes are carried downwards and are precipitated upon the bottom of the electrolytic vessel.

This precipitation is facilitated by arranging below the anode and the cathode a comparatively large circulation chamber, which can be effected by extending the elec trolytic vessel towards the bottom beyond the anodes and the cathode, so that the velocity of the circulating liquid near the bottom is very low and the impurities can consequently easily separate from the electrolyte and settle at the bottom.

In order to prevent the sediment from being stirred up partitions may be provided at the bottom of the vessel or container.

The temperature diiference existing in the electrolyte between the top and the bottom has the further advantage that the conductivity ofthe electrolyte is at the lower edge of the cathode about 20 to 30% less than at the upper edge, whereby the forma tion of bulbs at the lower edge of the cathode is considerably reduced.

In the drawing aflixed to this specification and forming part thereof two embodiments of my invention are illustrated by wa of example.

ig. 1 is, a vertical section modification and Fig. 2, a vertical section through a similar modification. Similar reference characters indicate similar parts in both figures of the through one Referring to Fig. 1, l is the electrolyte container or a vessel filled with the electrolyte. Into the liquid dips the cathode 2 which is rotatably suspended at 3. The

the process by the pulley 4 fixed upon it, in

cathode is rotated during the progress of known manner. The pulley-4 is driven by I means of the driving belt 5 and the pulley T on the shaft of the motor 6. 8 is the conductor which leads the current away from the cathode 2 by means of brush 18 sliding on contact ring 19. The anodes 9 are shown in end view and consist of horizontally disposed bars transversely set at an angle in the fashion of shutter bars. They are electrically connected with one another by the conductors 10. 11 is the conductor which supplies current to the anodes. The heating device is represented in the drawing by the parts 12, 13 and 14-. 12 is a tube of refractory material, for instance quartz. into which extend the two pipes 13 and 14. The pipe 14. is inserted into the pipe 13. By

the pipe 13 illuminating is introduced and by the ipe 14 compressed air, the mixture being ignited within the tube .2 on issuin from the nozzle 15. The heat thus generated heats the surrounding liquid. As the heating device should be as far as possible removed from the anodes, it is disposed closely around the cathode. lyte vessel is extended downwards beyond the anodes and the cathode. At its bottom partitions 16 are arranged between which the impurities deposit and which prevent this deposit from being stirred up by the circulating electrolyte. Figure 2 illustrates a in which the heating device is situated within the cathode, as hereinbefore described, in order to still further increase its distance from the anodes and thus to increase the effect. Here again 1 is thecontalner for the electrolyte'and 2 the cathode, WhlCh is shown in longitudinal section. The cathode is in this case'of tubular construction and is rotatably journaled at 3. 4, 5, 6 and 7 represent similar driving means for rotating the cathode as shown in Figure 1. Through the conductor 8 the current is led away from the cathode 2 by means of a brush 18 sliding on contact ring 19. The anodes 9 are constructed similar to Fig. 1. Into the central space 17 within the cathode extend the two pipes 13 and 14, the latter being contained within the former. The pipe 13 again supplies illuminating gas and the pipe 14 compressed air the mixture becoming ignited after issuing from the nozzle 15. The hot gases of combustion flow along the inner wall of the cathode and heat it and the surrounding liquid. The electrolyte container is again extended downward beyond the anodes and cathodes. Upon the bottom of the container are provided partition walls 16 between which the impurities settle and which prevent the stirring up of this sediment.

It will be readily understood that I do not limit myself to the exact details of construction or arrangement of the parts and similar construction The electro-* both electrodes.

that such arrangement may be modified within the scope of my claims without departing from the spiritof :my invention.

. What I claim as my invention and desire to secure by Letters Patent is 1. In an apparatus for producing electrolytic iron, the combination of a vessel con? taining the electrolyte, a cathode, an iron anode having a carbon content sufficient to leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, and means for supplying current to both electrodes.

2. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolytefa cathode, a cast iron anode having a free carbon content of at least 3%, to leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, and means for supplying current to both electrodes.

3. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, a cast iron anode having a'free carbon content of suflicient valueto leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, the anode surface constituting a multiple of the cathode surface, and means for supplying current to 4. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, a cast iron anode comprising a plurality of substantially horizontally disposed bars, eachhaving at least its underslde inclined in transverse direction, said bars having a free carbon content suificient to leave a coherent carbon skeleton of the bars after. their iron content has been electrolytically dissolved, the total surface of all anode bars constituting a multiple of the cathode surface, and means for supplying current to sai cathode and anode bars.

5. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, an iron anode having a carbon content sufiicient to leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, a heating device arranged within'the electrolyte and suitably disposed therein to maintain the temperature of the electrolyte the lowest near the bottom of the vessel, and means for supplying current to said cathode and anode.

6. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, an'iron ano'de having-a carbon content sufficient to leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, a heating device arranged within the electrolyte in proximity of the cathode ;-content has been electrolyticall 'l e in proximity 0 to cause the electrolyte to rise along the cathode and, to fall along the anode, and means for supplying current to said cathode and anode.

7 In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, a cast iron anode having a free carbon content of suflicient value to. leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, the anode surface constituting a multiple of the cathode surface, a heating device arranged within the electrolyte in proximity of the cathode to cause the electrolyte to rise along the cathode and to fall along the anode, and means for supplying current to sa d cathode and anode.

8. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, an iron anode having a carbon content sufficient to leave a coherent graphite skeleton after the anode iron has been electrolytically consumed, a heating device arran ed within the electrolyte in proximity of the cathode to cause the electrolyte to rise along the H cathode and to fall along the anode, said vesselhavlng a large circulating space for the electrolyte below both electrodes, and

means for supplying current to said electrodes. I

9. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, a cast iron anode having a free carbon content of sufficient value to leave a coherent. graphite skeleton after the anode iron has been electrolytically consumed, the anode surface constituting a multitple of the cathode surface, a heating device arranged within the electrolyte in proximity of the cathode to cause the electrolyte to rise along the d cathode and fall along the anode, said vessel having a large circulating space for the electrolyte below both electrodes, and partitions arranged on the bottom of the vessel and adapted to. receive and hold between them precipitations carried by the electrolyte into'said circulating space.

10. In an ap aratus for producing electrolytic iron, t e combination of a vessel containing the electrolyte, a cathode, a cast iron anode comprising a plurality of substantially horizontally disposed bars, each having at least its underside inclined in transverse direction, said bars having a free carbon content suflicient to leave a coherent carbon skeleton of the bars after their iron dissolved, the total surface of all anode ars constituting a multiple of the cathode surface, a heating device arranged within the electrothe cathode to cause e electrolyte to rise along the cathode and fall along the anode, said vessel having a large circulating space for the electrolyte -below both electrodes, and partitions arranged on the bottom of the vessel and adapted to receive and hold between them precipitations carried by the electrolyte into said circulating space.

11. In an apparatus for producing electrolytic iron, the combination of a vessel containing the electrolyte, a cathode, a cast iron anode comprising a plurality of substantially horizontally disposed bars, each having at least its underside inclined in transverse direction, said bars having a free carbon content sufficient to leave a; coherent carbon skeleton of the bars after their iron content has been electrolytically dissolved, the total surface of all anode bars constituting a multiple of the cathode surface, a heating device arranged within the electrolyte in proximity of the cathode to cause the electrolyte to rise along the cathode and fall along the anode, said vessel having a large circulating space for the electrolyte below both electrodes, and means for supplying current to said electrodes, the current having a potential of less than one volt.

In testimony whereof I aflix my signature.

EMIL DUHME. 

